THE LUNAR ACHILLES AS A COMPARISON OF OSTEOPOROSIS SCREENING TOOLS: THE HEEL ULTRASOUND MEASUREMENT VERSUS THE CALCULATED RISK ASSESSMENT TOOL

M. Gambacciani, A. R. Genazzani

Department of Obstetrics and Gynecology,University of Pisa, Pisa, Italy (2004)

 

Heel ultrasound can provide low-cost measurements to identify women likely to have osteoporosis at the hip or spine as measured by DXA. Here we determined the specific T-score cutpoint on the Lunar Achilles InSight (GE Medical Systems) that detects 90% of individuals with osteoporosis (T-score ≤ -2.5) at either hip or spine. The Achilles InSight is an imaging heel ultrasonometer with 8-10 second measurement time (the complete examination takes 3-5 minutes). We also compared the performance of heel ultrasound screening to a simple risk assessment tool based on weight and age.

DXA scans of the spine and hip were obtained in 272 women aged 40 to 83 years (mean age 58 7 years) using a Lunar DPX (GE Medical Systems). All subjects also had a heel ultrasound measurement using the Achilles InSight. Osteoporosis was diagnosed if the lowest DXA T-score at spine (L1-L4) or hip (total femur) was ≤ -2.5. The heel T-score cutpoint with 90% sensitivity was determined using ROC analysis. For each subject the value of the osteoporosis risk assessment tool (risk tool in short; defined as (Weight in kg age)*0.2)) was also calculated.

From the DXA results, 54 of 272 patients were classified as osteoporotic. At a heel T-score of 1.0, sensitivity was 91% and specificity was 46%. Based on ROC analysis, the area under the curve (AUC) for the heel T-score was 0.79, which was significantly greater than the AUC for the risk tool, 0.69 (p < 0.05). The AUC for the combination of the heel T-score and the risk tool was 0.81 (0.75-0.87).

We conclude that the Achilles bone ultrasonometer can be used as a valid screening tool for osteoporosis, with over 90% sensitivity at a T-score of 1.0 and good specificity. Moreover, the Achilles performs significantly better in identifying those patients who should be considered for spine and hip bone density assessment compared to the calculated osteoporosis risk assessment tool.

 

 

AUC

90% Sensitivity Cutpoint

Sensitivity

Specificity

Heel T-score

0.79 (0.72-0.85)

-1.0

90.7%

46.3%

Risk Tool

0.69 (0.62-0.77)

2.4

90.7%

28.9%